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| 1 // Copyright 2015 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 package memory | |
| 6 | |
| 7 import ( | |
| 8 "errors" | |
| 9 "sync" | |
| 10 | |
| 11 "golang.org/x/net/context" | |
| 12 | |
| 13 "appengine/datastore" | |
| 14 ) | |
| 15 | |
| 16 type memContextObj interface { | |
| 17 sync.Locker | |
| 18 canApplyTxn(m memContextObj) bool | |
| 19 applyTxn(c context.Context, m memContextObj) | |
| 20 | |
| 21 endTxn() | |
| 22 mkTxn(*datastore.TransactionOptions) (memContextObj, error) | |
| 23 } | |
| 24 | |
| 25 type memContext []memContextObj | |
| 26 | |
| 27 var _ = memContextObj((memContext)(nil)) | |
| 28 | |
| 29 func newMemContext() memContext { | |
| 30 return memContext{ | |
| 31 newTaskQueueData(), | |
| 32 newDataStoreData(), | |
| 33 } | |
| 34 } | |
| 35 | |
| 36 type memContextIdx int | |
| 37 | |
| 38 const ( | |
| 39 memContextTQIdx memContextIdx = iota | |
| 40 memContextDSIdx | |
| 41 ) | |
| 42 | |
| 43 func (m memContext) Get(itm memContextIdx) memContextObj { | |
| 44 return m[itm] | |
| 45 } | |
| 46 | |
| 47 func (m memContext) Lock() { | |
| 48 for _, itm := range m { | |
| 49 itm.Lock() | |
| 50 } | |
| 51 } | |
| 52 | |
| 53 func (m memContext) Unlock() { | |
| 54 for i := len(m) - 1; i >= 0; i-- { | |
| 55 m[i].Unlock() | |
| 56 } | |
| 57 } | |
| 58 | |
| 59 func (m memContext) endTxn() { | |
| 60 for _, itm := range m { | |
| 61 itm.endTxn() | |
| 62 } | |
| 63 } | |
| 64 | |
| 65 func (m memContext) mkTxn(o *datastore.TransactionOptions) (memContextObj, error
) { | |
| 66 ret := make(memContext, len(m)) | |
| 67 for i, itm := range m { | |
| 68 newItm, err := itm.mkTxn(o) | |
| 69 if err != nil { | |
| 70 return nil, err | |
| 71 } | |
| 72 ret[i] = newItm | |
| 73 } | |
| 74 return ret, nil | |
| 75 } | |
| 76 | |
| 77 func (m memContext) canApplyTxn(txnCtxObj memContextObj) bool { | |
| 78 txnCtx := txnCtxObj.(memContext) | |
| 79 for i := range m { | |
| 80 if !m[i].canApplyTxn(txnCtx[i]) { | |
| 81 return false | |
| 82 } | |
| 83 } | |
| 84 return true | |
| 85 } | |
| 86 | |
| 87 func (m memContext) applyTxn(c context.Context, txnCtxObj memContextObj) { | |
| 88 txnCtx := txnCtxObj.(memContext) | |
| 89 for i := range m { | |
| 90 m[i].applyTxn(c, txnCtx[i]) | |
| 91 } | |
| 92 } | |
| 93 | |
| 94 // Use adds implementations for the following gae/wrapper interfaces to the | |
| 95 // context: | |
| 96 // * wrapper.Datastore | |
| 97 // * wrapper.TaskQueue | |
| 98 // * wrapper.Memcache | |
| 99 // * wrapper.GlobalInfo | |
| 100 // | |
| 101 // These can be retrieved with the "gae/wrapper".Get functions. | |
| 102 // | |
| 103 // The implementations are all backed by an in-memory implementation, and start | |
| 104 // with an empty state. | |
| 105 // | |
| 106 // Using this more than once per context.Context will cause a panic. | |
| 107 func Use(c context.Context) context.Context { | |
| 108 if c.Value(memContextKey) != nil { | |
| 109 panic(errors.New("memory.Use: called twice on the same Context")
) | |
| 110 } | |
| 111 c = context.WithValue( | |
| 112 context.WithValue(c, memContextKey, newMemContext()), | |
| 113 giContextKey, &globalInfoData{}) | |
| 114 return useTQ(useDS(useMC(useGI(c)))) | |
| 115 } | |
| 116 | |
| 117 func cur(c context.Context) (p memContext) { | |
| 118 p, _ = c.Value(memContextKey).(memContext) | |
| 119 return | |
| 120 } | |
| 121 | |
| 122 type memContextKeyType int | |
| 123 | |
| 124 var memContextKey memContextKeyType | |
| 125 | |
| 126 // weird stuff | |
| 127 | |
| 128 // RunInTransaction is here because it's really a service-wide transaction, not | |
| 129 // just in the datastore. TaskQueue behaves differently in a transaction in | |
| 130 // a couple ways, for example. | |
| 131 // | |
| 132 // It really should have been appengine.Context.RunInTransaction(func(tc...)), | |
| 133 // but because it's not, this method is on dsImpl instead to mirror the official | |
| 134 // API. | |
| 135 // | |
| 136 // The fake implementation also differs from the real implementation because the | |
| 137 // fake TaskQueue is NOT backed by the fake Datastore. This is done to make the | |
| 138 // test-access API for TaskQueue better (instead of trying to reconstitute the | |
| 139 // state of the task queue from a bunch of datastore accesses). | |
| 140 func (d *dsImpl) RunInTransaction(f func(context.Context) error, o *datastore.Tr
ansactionOptions) error { | |
| 141 curMC := cur(d.c) | |
| 142 | |
| 143 txnMC, err := curMC.mkTxn(o) | |
| 144 if err != nil { | |
| 145 return err | |
| 146 } | |
| 147 | |
| 148 defer func() { | |
| 149 txnMC.Lock() | |
| 150 defer txnMC.Unlock() | |
| 151 | |
| 152 txnMC.endTxn() | |
| 153 }() | |
| 154 | |
| 155 if err = f(context.WithValue(d.c, memContextKey, txnMC)); err != nil { | |
| 156 return err | |
| 157 } | |
| 158 | |
| 159 txnMC.Lock() | |
| 160 defer txnMC.Unlock() | |
| 161 | |
| 162 if curMC.canApplyTxn(txnMC) { | |
| 163 curMC.applyTxn(d.c, txnMC) | |
| 164 } else { | |
| 165 return datastore.ErrConcurrentTransaction | |
| 166 } | |
| 167 return nil | |
| 168 } | |
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Chromium Code Reviews
Issue 1240573002:
Reland: Refactor current GAE abstraction library to be free of the SDK* (Closed)
Base URL: https://chromium.googlesource.com/infra/infra.git@master